Speed Rating Index Of Vehicle Tyres

Learning About Load & Speed Rating Index Of Vehicle Tyres

As a vehicle owner, if you’ve been confused seeing those numbers & letters on the side of your car tyres, then you’re not alone. Loads of people like you also don’t know what those numbers & letters mean, which is why it’s essential to educate vehicle owners about the car tyres they purchase. 

By clearing up the confusion and helping you understand more about the concept behind those numbers & letters, will help you choose the ideal tyres for your car. Hence, without any further ado, let’s get started. 

What Do You Mean By The Tyre Load Index Rating?

According to a well-known service provider for wheel alignment in Auckland, the load index of a tyre is the easiest way to describe the total load capacity of a vehicle tyre. This means that the said number is the maximum threshold limit that the tyre can carry. 


For instance, if your tyre has a designation of 225/40 R18 94Y, then the numbers can be broken down into the following concepts:

  • Tire width – 225 mm
  • Aspect ratio – 40%
  • Radial Construction – R
  • Rim diameter – 18 inches
  • Load index – 94
  • Speed index – Y

Therefore, it can be easily seen from the above-mentioned example that the load index is rated at 94. But, what does that number signify? Well, 94 load index corresponds to a load rating of 1477 lbs, which means that the load-carrying capacity of all the tyres will be 4×1477 lbs= 5908 lbs.

There’s a whole load index chart that you can refer to before purchasing your new tyres. The load index starts at 70 and goes up to a maximum of 126. 70 load index corresponds to 739 lbs, while 126 load index corresponds to 3748 lbs. 

Thus, when you decide to change your vehicle tyres, always choose the ones that have the same or higher load index rating as the previous ones. Using a low load index tyre will simply overload the same and will lead to blowouts, damage or even premature wear & tear.

What Do You Mean By Tyre Speed Index Rating?

Similar to the tyre load index rating, the speed index rating is an easier method to showcase how faster a tyre can move in an ideal condition. But, instead of using numbers, it utilises letters, unlike the load index rating. 

Continuing with our above-mentioned example, the speed index rating was Y. The letter Y corresponds to a maximum speed limit of 186 miles per hour, which is the fastest on the tyre speed rating index chart. 

The speed index rating starts at L (75 miles per hour) and ends at Y (186 miles per hour).

For any additional questions, be sure to contact us at any time.

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